Slip coupling and weston brake for hoists

ABSTRACT

In a hoist, a Weston type brake mechanism is formed with a friction disk integral with the load shaft, and the driving element of the Weston brake mechanism as well as the ratcheted locking disk of the brake are mounted for rotation in the axis of the load shaft and are effective through the integral friction disk to control the load shaft directly so as to control the load at all times. The driving element of the Weston brake mechanism is made of two parts, one of which is a gear in frictional relationship to the other part, and held assembled thereto by means entirely contained between the two parts so that they function effectively as one. Any failure in the frictional relationship will not affect the functioning of the Weston brake mechanism to control the load.

United States Patent [1 1 Suez et al.

[451 Sept. 4, 1973 SLIP COUPLING AND WESTON BRAKE FOR IIOISTS [75]Inventors: Kang Suez; Glenn S. Smith, both of Forrest City, Ark.

[52] Cl. 192/16, 64/30 R, 254/187 R [51] Int. Cl. Fl6d 13/30, Fl6d 67/02[58] Field of Search 192/16, 15; 64/30 R [56] References Cited UNITEDSTATES PATENTS 2,501,096 3/1950 Robins et a1 192/15 3,493,087 2/1970Freeman et a1 192/16 2,642,266 6/1953 Dotson 192/16 X 2,770,339 11/1956Dotson 192/16 3,605,443 9/1971 Redelman 154/30 R FOREIGN PATENTS ORAPPLICATIONS 1,106,250 7/1955 France 6 4/30 Primary Examiner-Benjamin W.Wyche Attorney-Leslie I-I. Blair et a1.

[57] ABSTRACT In a hoist, a Weston type brake mechanism is formed with afriction disk integral with the load shaft, and the driving element ofthe Weston brake mechanism as well as the ratcheted locking disk of thebrake are mounted for rotation in the axis of the load shaft and areeffective through the integral friction disk to control the load shaftdirectly so as to control the load at all times. The driving element ofthe Weston brake mechanism is made of two parts, one of which is a gearin frictional relationship to the other part, and held assembled theretoby means entirely contained between the two parts so that they functioneffectively as one. Any failure in the frictional relationship will notaffect the functioning of the Weston brake mechanism to control theload.

7 Claims, 4 Drawing Figures PATENTEUSEP 41m 3756359 INVENTORS 54/52 BY6. 6. 5/14/77/ TE/IGA/O & TODDV 47702/1/5 5 SLIP COUPLING AND WESTONBRAKE FOR IIOISTS This invention relates to a hoist, and moreparticularly, to braking mechanism and load limiting mechanism for ahoist.

Hoists equipped with load limiting mechanism, and with load brakes, arenaturally quite old in the art. A particularly effective type of brakemechanism utilized in the hoist art is known as a Weston brake, and onesuch mechanism is found in the Schroeder US. Pat. No. 2,244,221. Thismechanism embodies broadly a ratcheted brake disk that is adapted forfree rotation in one direction, corresponding to a lift direction, butis held by a cooperating ratchet pawl against movement in a reversedirection. The load lifting and lowering means, including an axiallymovable driving element, are locked to the ratcheted disk by frictionunder certain conditions, as is well understood in the art, to hold theload against lowering movement. Release from the ratcheted disk topermit lowering of the load is easily effected by operating the loadlifting means in a lowering direction.

A load brake similar to that shown by Schroeder is shown in the JuergensU.S. Pat. No. 1,867,409. There, the disk equivalent to the ratcheteddisk of Schroeder, is held by a series of detents against rotation in adirection corresponding to the lowering of the load, and functionstherefore just as does the Schroeder ratcheted disk to control the load.As a further detail, in Juergens a cam mechanism is utilized to bringabout locking of the load lifting mechanism to the ratcheted disk,whereas in Schroeder a cam screw is utilized for the particular purpose.

Many means have been developed in the prior art for preventing overload,and one mechanism that has been suggested is a friction clutch such asfound in the Robins et al. US. Pat. No. 2,501,096. Since a hoist must bedesigned to occupy as little space as possible, it is obvious that afriction clutch such as is found in Robins et al. is not entirelysatisfactory. Thus, it is obvious that the friction disks utilized byRobins must be assembled relatively to one another and be retained inassembled position and that this requires space and a considerablenumber of parts.

Further, so far as is known, Weston brakes and friction clutches of thetype heretofore utilized, have never been combined in effectiverelationship in a hoist. To understand this point, it will be well toconsider that if the brake mechanism is in geared relation to the loadshaft of the hoist, any failure of mechanism between the brake and theload shaft will obviously result in the load being released. Further,any direct association of the load limiting friction clutch mechanismand a brake of the class here being discussed, may also result infailure of the brake mechanism. This difficulty is naturally compoundedwhere the brake mechanism is mechanically displaced from the loadthrough the utilization of several elements between it and the loadshaft.

As a feature of the invention of this application, a brake mechanism ofthe Weston type is utilized directly with the load shaft. Thus, abraking disk is secured integrally to the load shaft and rotatestherewith so as to be locked to the ratcheted disk, if a disk such asfound in the Schroeder patent is utilized, or with the detent controlleddisk, if a disk such as found in Juergens is utilized.

As a further feature of the invention, a frictional overload clutch isformed as an integral part of the braking mechanism, but in a positionin that mechanism where it cannot possibly interfere with theapplication of the brake. As a more particular feature of this part ofthe invention, the axially movable driving element of the Weston brakeis formed as an assembly of two parts, with frictional meanstherebetween. One of the two parts is a circular braking disk, while theother part is a circular gear formed as a ring, with an inner ringsurface fitted on the outer circular periphery of the disk.

As a more particular feature of this concept, the two parts of theaxially movable driving element are held together by means extendingtherebetween, so that there are no external forces applied thereagainst,and so that the two parts will function normally as one part equivalentto the driving element of a Weston brake mechanism.

In summary, it may be stated that the invention of this applicationcontributes the concept of a Weston brake applied directly to the loadshaft of a hoist. It may further be stated that the concept of theinvention also includes the utilization of a Weston brake directly onthe load shaft together with a load limiting mechanism directlyassociated and built into parts of the Weston brake mechanism. It willbe obvious further, that the invention here includes the additionalconcept of a novel load limiting frictional clutch, and particularly aclutch between two parts of an element of the Weston brake. The value ofthis last feature resides in the fact that no spring means or othermechanism will interfere in any way whatsoever with the normal operationof the driving element of the Weston brake, nor with its endwisemovement required for both gripping the ratcheted or detent controlleddisk, or for loosening its relation to the ratcheted or detentcontrolled disk.

The novel features that are believed to be characteristic of thisinvention are set forth with particularity in the claims appendedhereto. The invention itself, however, both as to its organization andmethod of operation, together with further objects and advantagesthereof can best be understood by reference to the following descriptiontaken in connection with the accompanying drawings in which:

FIG. 1 is an elevation of a hoist of a type to which the invention maybe applied;

FIG. 2 is a partial section taken along line 2-2 of FIG. 1;

FIG. 3 is a section taken along line 3-3 of FIG. 2; and

FIG. 4 is an isometric view of a cam utilized in connection with theWeston brake mechanism.

Referring now more particularly to the drawings, a hoist to which theinvention may be applied is best shown in FIG. 1 where it is designatedgenerally by reference numeral 10. It includes a supporting hook 11, anda load supporting hook 12 at the end of a load chain 13 that is adaptedto be moved upwardly or downwardly through winding on a standard type ofsheave 15 best indicated in FIG. 2. It will naturally be understood bythose skilled in the art that while the hoist is here designed forutilization with a chain 113, it may also be used in combination with acable, a roller and link chain, or any other hoisting combination. Theimportant point to consider is the fact that the load sheave 15 isformed integrally with a load shaft 16, this being the shaft that mustbe rotated in order to lift and lower the load through rotation of thesheave in either of opposed directions.

For rotating the load shaft 16, there is utilized an electric motor (notshown), whose armature is fixed to an operating shaft 17. This operatingshaft rotates at one end on a roller bearing 18, and terminates at 19 ina coupling 20 through which it is connected to a second operating shaft21 traversing a central bored opening in the load shaft 16. Operatingshaft 21 is suitably mounted in bearings as shown and carries a pinion22 engaging the teeth of a gear 23 mounted at one end of a shaft 24.Shaft 24 is suitably supported in bearings 25 in the hoist casing and isequipped with a relatively long pinion 26 in engagement with the teeth27 of a circular gear 28.

Circular gear 28 is one of the two parts of the hoist driving elementutilizing a frictional clutch as earlier described generally. The otherpart of this element is designated by reference numeral 29, and it is apart of the Weston brake mechanism. Thus, it has a frictional surface atone side thereof in engagement with a friction disk 31 that bearsagainst the locking disk 32 which in turn bears against a friction disk33 adapted to engage friction disk 34 that is fixed, as by a key, to theload shaft 16.

The locking disk 32 may be formed as a ratcheted disk cooperable with apawl, such as found in many Weston brake mechanisms, and as illustratedin the Schroeder patent. It may, however, be also a detent controlleddisk as shown in FIG. 3, similar to the disk found in the Juergenspatent earlier referred to.

It is thought that detailed showing of the Weston brake mechanism,including the disk 32, need not be presented since the construction isquite old in the art and is well shown in the Juergens patent. It may bewell to indicate generally, however, that the locking disk 32 is freelyrotatable on the load shaft 16, but will not rotate in a load loweringdirection through coaction of the detents 35 carried by a clutch ring36, with cam slots 37 in the disk 32. As set forth in J uergens,rotation in one direction of the locking disk 32 is possible so as topermit the disk 32 to rotate in lifting direction with the friction disk34 and the shaft 16. However, the locking disk 32 will not rotate in areverse direction, and therefore will prevent rotation of the frictiondisk 34 and the shaft 16 when the disk 32 is frictionally locked to thedisk 34, in accordance with the manner in which Weston hoist brakes areoperated.

The two-part driving element 28, 29 is rotatably mounted on the loadshaft 16, and is movable endwise relatively to the load shaft 16 throughcoaction with a cam 40 that operates similarly to the cam employed byJuergens. Cam 40 is itself, through teeth 41 locked to the load shaft16, and since driving element 28, 29 is freely rotatable on the loadshaft, it is obvious that any relative motion between the load shaft andthe element 28, 29, will effect axial movement of element 28, 29 againstthe friction disk 31 to bind all of the parts including the disk 32, tothe disk 34. Upon such binding, it is obvious that load lifting rotationof shaft 16 is possible through the intermediary of friction disk 34.The load shaft 16 will, however, be locked against lowering movement ofthe load through the locking of the locking disk 32 by the detents 35unless the element 28, 29 is backed off or moved axially on shaft 16 torelease the friction between the several parts of the Weston brake, asis common in the art.

The two parts of element 28, 29 are held together through frictionalmeans 45 therebetween, these frictional means being in the form of africtional surface formed on either or both of the parts and occupyingan angular position as shown. A spring disk 46 carried by the part 29presses against the circular gear portion 28, urging it to the left asshown in FIG. 2 and against the part 29 so as to bring about a bindingof the parts through the frictional means 45. It is readily seen, thatbecause of the angular relation between the parts 28 and 29, the part 29will actually limit the movement of the part 28 in one directionrelatively to the part 29. Further, the spring disk 46 will preventreverse movement of the two parts relatively to one another under normaloperation conditions.

Therefore, the two parts 28 and 29 will act as one element and willactually be retained in assembled relation by the spring means 46 andthe friction clutch surfaces at 45. The spring disk 46 is itself held inposition by a retaining ring 47 also carried by the part 29. It cantherefore be said that the two parts 28, 29 are held as a single unitnormally, through means entirely found between the two parts. Therefore,there is nothing that in any way affects the relationship of the twoparts 28, 29 relatively to one another to form a single element, andthere is nothing that interferes with the combined axial movement of thetwo parts through action of the cam 40. Naturally, in all positionsthereof, teeth 27 of gear 28 will mesh with long pinion 26 of shaft 24.

It will be appreciated, that while a cam 40 similar to the cam found inJuergens is here utilized to contribute axial motion to element 28, 29,the combined parts 28, 29 may be mounted on a screw formed on the shaft16 as is common in many Weston type hoists, and as is found in theSchroeder patent.

It will now be appreciated that rotation of the shaft 17 will throughits clutch relation to the shaft 21 bring about the rotation of thepinion 22, the gear 23, the shaft 24, and the circular gear 28. If theload is not greater than that which the friction clutch means 45 willeffectively handle, the element 28, 29 will rotate, and through the cam40 will be moved endwise to bring about a gripping of all of the partson the shaft 16 relatively to the disk 34 fixed to the shaft 16. Thiswill bring about rotation of the sheave l5 and a lifting of the load. Byrotation of shaft 17 in a reverse direction, the element 28, 29 will bebacked off axially slightly relatively to disk 32 to permit lowering ofthe load through a decrease of the friction between the several partsmounted on the shaft 16. If the shaft 16 then tends to rotate tooswiftly, there will be a reverse relative movement between the element28, 29 and the cam 40 secured to the shaft 16, and the load shaft 16will again be locked or appropriately restrained by friction relative tothe disk 32. The disk 32 will of course always prevent lowering movementof shaft 16 when it is locked by friction to the other parts mountedabout shaft 16.

It will be seen that because the disk 34 is fixed to the load shaft 16,any destruction of any of the parts utilized to drive the part 29 ofelement 28, 29, will not in any way permit release of the load.Moreover, if friction at 45 is relieved in some manner, the part 29 willstill be moved endwise by the cam 40 at all times to lock the disk 34 tothe ratcheted or locking disk 32, as

will be obvious. It is further obvious that any overload will cause aslipping action at 45 to prevent lifting of the load, while not in anymanner decreasing the effectiveness of the part 29 to control the brakeof the Weston mechanism as fully set forth. Therefore, it is believedthat the very considerable contribution of the concept set forth willnow be obvious, and that the merits of the invention will be appreciatedby persons who are skilled in the art.

We now claim:

1. In a hoist of the class described, a load shaft on which the weightof a load is supported, a load lifting member such as a chain or thelike, a winding member fixed to said load shaft and rotatable integrallytherewith for winding and unwinding said load lifting member whereby tolift and lower a load, a Weston brake mounted to said load shaftcomprising a disk fixed to said load shaft, a ratcheted locking diskrotatably mounted on said load shaft for rotation relatively thereto, adriving element rotatably mounted on said load shaft for rotation andaxial movement relatively thereto, said driving element being formed oftwo parts, one of said parts being a circular disk rotatably mounted onsaid load shaft and having side surfaces connected by a peripheralsurface generally extending axially along said load shaft, the otherpart being a circular gear formed as a ring having an inner ring surfacefitted on said axially extending surface of said circular disk, meansmounted between said axially extending surface and said inner ringsurface for yieldingly compelling the integral rotation of said twoparts, and means whereby rotation of said driving element relatively tosaid load shaft effects the axial movement of said driving elementrelatively to said load shaft to bind said ratcheted disk to said diskfixed to said load shaft.

2. In the combination of claim 1, the feature that the axial movement ofsaid driving element is contributed by means fixed to said shaft andincluding gear means engaging the teeth of said circular gear to drivesaid two part driving element thereby.

3. In the combination of claim 1, the feature that said outer peripheralsurface and said inner ring surface each form a conical surfaceextending along the axis of rotation thereof, and spring means pressingsaid circular gear axially of said disk to effect frictional binding ofsaid conical surfaces.

4. In a hoist of the class utilizing a Weston brake comprising afriction disk fixed to a brake shaft, a ratcheted locking disk, adriving element, and means for moving said driving element axially ofsaid shaft upon rotation thereof relatively to said shaft, the im'provement that comprises forming said driving element of two parts, oneof said parts being a circular disk rotatably mounted on said shaft andhaving an outer circular peripheral surface extending generally alongthe length of said shaft, the other part being a circular gear formed asa ring with an inner ring surface extending generally along the lengthof said shaft and being fitted on said outer circular peripheralsurface, said circular gear having an outer ring surface with gear teeththereon, clutch means mounted between said outer peripheral surface andsaid inner ring surface for yieldingly compelling the integral rotationof said two parts with said shaft, and gear means engaging said teeth ofsaid circular gear.

5. In the combination of claim 4, the feature that said means yieldinglycompelling the integral rotation of said two parts is friction meansmounted between said outer peripheral surface and said inner ringsurface.

6. In the combination of claim 4, the feature that said outer peripheralsurface and said inner ring surface each form a conical surfaceextending along the axis of said brake shaft, and including spring meanspressing said circular gear axially of said disk to effect frictionalbinding at said conical surfaces.

7. In the combination of claim 4, the feature that said means yieldinglycompelling rotation of said two parts includes spring means extendingalong a side surface of said two parts and forming therewith a selfcontained assembly.

1. In a hoist of the class described, a load shaft on which the weightof a load is supported, a load lifting member such as a chain or thelike, a winding member fixed to said lOad shaft and rotatable integrallytherewith for winding and unwinding said load lifting member whereby tolift and lower a load, a Weston brake mounted to said load shaftcomprising a disk fixed to said load shaft, a ratcheted locking diskrotatably mounted on said load shaft for rotation relatively thereto, adriving element rotatably mounted on said load shaft for rotation andaxial movement relatively thereto, said driving element being formed oftwo parts, one of said parts being a circular disk rotatably mounted onsaid load shaft and having side surfaces connected by a peripheralsurface generally extending axially along said load shaft, the otherpart being a circular gear formed as a ring having an inner ring surfacefitted on said axially extending surface of said circular disk, meansmounted between said axially extending surface and said inner ringsurface for yieldingly compelling the integral rotation of said twoparts, and means whereby rotation of said driving element relatively tosaid load shaft effects the axial movement of said driving elementrelatively to said load shaft to bind said ratcheted disk to said diskfixed to said load shaft.
 2. In the combination of claim 1, the featurethat the axial movement of said driving element is contributed by meansfixed to said shaft and including gear means engaging the teeth of saidcircular gear to drive said two part driving element thereby.
 3. In thecombination of claim 1, the feature that said outer peripheral surfaceand said inner ring surface each form a conical surface extending alongthe axis of rotation thereof, and spring means pressing said circulargear axially of said disk to effect frictional binding of said conicalsurfaces.
 4. In a hoist of the class utilizing a Weston brake comprisinga friction disk fixed to a brake shaft, a ratcheted locking disk, adriving element, and means for moving said driving element axially ofsaid shaft upon rotation thereof relatively to said shaft, theimprovement that comprises forming said driving element of two parts,one of said parts being a circular disk rotatably mounted on said shaftand having an outer circular peripheral surface extending generallyalong the length of said shaft, the other part being a circular gearformed as a ring with an inner ring surface extending generally alongthe length of said shaft and being fitted on said outer circularperipheral surface, said circular gear having an outer ring surface withgear teeth thereon, clutch means mounted between said outer peripheralsurface and said inner ring surface for yieldingly compelling theintegral rotation of said two parts with said shaft, and gear meansengaging said teeth of said circular gear.
 5. In the combination ofclaim 4, the feature that said means yieldingly compelling the integralrotation of said two parts is friction means mounted between said outerperipheral surface and said inner ring surface.
 6. In the combination ofclaim 4, the feature that said outer peripheral surface and said innerring surface each form a conical surface extending along the axis ofsaid brake shaft, and including spring means pressing said circular gearaxially of said disk to effect frictional binding at said conicalsurfaces.
 7. In the combination of claim 4, the feature that said meansyieldingly compelling rotation of said two parts includes spring meansextending along a side surface of said two parts and forming therewith aself contained assembly.